DE102014209384A1 - Valve with a magnetic actuator - Google Patents

Abstract

A magnetic actuator (1), which is used in particular for devices (2) of internal combustion engines, comprises a magnetic coil (3) and at least one ferromagnetic component (4). In this case, a magnetic flux (9) caused by the magnetic coil (3) can be guided via the component (4). At the ferromagnetic component (4), a magnetic throttle point (19) is provided, which serves to balance the magnetic flux (9). For example, the magnetic throttle point (19) by a local structural transformation (19) of a ferromagnetic material of the ferromagnetic component (4) are formed. Further, a valve (2) having such a magnetic actuator (1) and a method of manufacturing such a magnetic actuator (1) are given.

Description

State of the art

The invention relates to a magnetic actuator, which is used in particular for devices of internal combustion engines, and a valve with such a magnetic actuator and a method for producing such a magnetic actuator. Specifically, the invention relates to the field of fuel injection systems of internal combustion engines.

From the DE 10 2006 021 741 A1 For example, an injector for injecting fuel into a combustion chamber of an internal combustion engine is known in which a control valve is actuated via a magnet. As soon as the magnet is energized, a magnetic field is formed which acts on an armature. The armature is accommodated in an armature space, in which fuel flows out of a control chamber when the control valve is open. To start an injection process, the magnet is energized and to end the injection process, the energization of the magnet is stopped.

For a magnetic switching valve, as it is from the DE 10 2006 021 741 A1 is known, there is the problem that arise in the manufacturing tolerances for the switching behavior of the magnetic switching valve or for acting on the armature magnetic tightening force, the reduction by tight tolerance specifications is costly. In particular, the air gap at the armature resulting from the geometric tolerances and scattering in the magnetic properties of the individual components play a role. Such production controls affect in functional variations, resulting in, for example, variations in the dynamic metering. Optionally, such scattering can be counteracted by batchwise adaptation of the residual air gap. An individual adaptation is often not possible due to the constructive effort.

Disclosure of the invention

The magnetic actuator according to the invention with the features of claim 1, the valve according to the invention with the features of claim 7 and the inventive method with the features of claim 9 have the advantage that an improved design and operation are possible. In particular, tolerance-related scattering in the switching behavior can be reduced.

The measures listed in the dependent claims advantageous developments of the specified in claim 1 magnetic actuator, the valve specified in claim 7 and the method specified in claim 9 are possible.

The magnetic actuator has the ferromagnetic component on which a magnetic throttle is provided, which serves to balance the magnetic flux. In this case, at least one such magnetic throttle point is provided. Thus, it is also possible to provide a plurality of magnetic throttle points which serve for balancing the magnetic flux, if this is expedient in the respective application. The ferromagnetic component for the magnetic actuator can be realized in different ways. In one possible embodiment, the magnetic actuator may already comprise the ferromagnetic component as an independent product and be manufactured and distributed independently of the device in which it is installed. In another possible embodiment, the ferromagnetic component of the magnetic actuator may be formed by a housing part of the device, in which the magnetic coil, the armature and optionally further component for the magnetic actuator are inserted. Specifically, the ferromagnetic component of the magnetic actuator can thus also be formed by a housing part of a valve housing of a valve, wherein the thus configured magnetic actuator is used to switch the valve. The functionality of the magnetic actuator is given in this case only after the assembly of the valve.

It is advantageous that at least one magnetic throttle point is formed by a local structural transformation of a ferromagnetic material of the ferromagnetic component. Specifically, it is advantageous in this case that the magnetic throttle point is formed by an austenitic microstructure of the ferromagnetic material. The material for the ferromagnetic component may be optimized in terms of magnetic conductivity. By heating, a structural change can then be caused in defined material areas, which changes the magnetic properties. In particular, a structural transformation into austenitic microstructure can change the magnetic properties strongly enough that the relevant effect can be utilized. If a material optimized for magnetic conductivity is used, the magnetic flux at the throttle point produced thereby will be reduced from the initial state by suitable local heating. This can reduce the magnetic flux, allowing the overall properties to be adjusted.

Thus, the magnetic flux can be controlled reduced. In this case, a permanent throttling of the magnetic flux can be achieved by various approaches. A Possibility exists in the local change of the material characteristics, for example by local heating, which can take place for example by a laser.

Another possibility for the controlled reduction of the magnetic flux consists in a reduction of the flowed through cross section of the component. This can be done for example by removing material, which can be done for example by a laser. The removal of material can also be done in other ways.

Thus, it is advantageous that the magnetic throttle point is formed by a recess on the ferromagnetic component. Such a recess is preferably formed with a laser beam. Specifically, the magnetic throttle body can be formed by machining the ferromagnetic component with a pulsed laser beam, wherein the laser beam acts on the ferromagnetic component.

For example, can be reduced in a step by annular removal of a groove on the ferromagnetic component of the magnetically effective cross section until a target value for the magnetic flux or a target value for a magnetic force is reached. Preferably, laser systems are used for this purpose whose pulse duration is so short that a removal can be achieved without further thermal damage to the material of the ferromagnetic component. The laser ablation can be done using a scanner optics. The laser pulses can be generated here as ps laser pulses (picosecond laser pulses) or fs laser pulses (femtosecond laser pulses).

The magnetic actuator may for example consist of an assembly comprising an armature, a needle, the magnetic coil, a membrane and a body. This assembly can be placed in a device to allow simultaneous energization of the solenoid coil and measurement of a needle force acting on the needle. The body can be configured as a polar body. Thus, the actual value of the needle force corresponding to a desired magnetic behavior can be determined. From the knowledge of the needle force and the applied current can be deduced on the magnetic flux. As a result, the magnetic flux can be adjusted.

Another possibility for the design of the magnetic throttle point is the introduction of a blind weld, over which the magnetic flux can be adjusted. Therefore, it is also advantageous that the magnetic throttle point is formed by a blind weld on the ferromagnetic component.

It is also advantageous that the ferromagnetic component is at least substantially rotationally symmetrical and that the throttle point is formed with a rotationally symmetrical configuration on the ferromagnetic component. In this way, an optionally desired, rotationally symmetrical design of the magnetic field can be ensured in order to achieve an advantageous switching behavior.

It is also possible that at least one magnetic throttle point is provided on a second ferromagnetic component, which also serves to balance the magnetic flux. This applies accordingly for other ferromagnetic components. In order to reduce the processing effort, it will generally be expedient, however, that precisely one ferromagnetic throttle point is provided on only one ferromagnetic component, which serves for balancing the magnetic flux.

The ferromagnetic component on which the throttle point is formed for balancing the magnetic flux may be the armature, a hollow body or another component of the magnetic actuator. Thus, with regard to the respective application, a suitable component for balancing the magnetic flux can be processed and thereby modified.

The geometric design and the material-specific properties of the respective component determine the extent to which the respective component is conducive to the largest possible magnetic flux. Viewed the other way around, bottlenecks for the magnetic flux (magnetic flux) arise at certain components and possibly at certain locations of the components. Such bottlenecks are characterized by the fact that geometrical and / or modifications affecting the material structure affect the magnetic flux to a comparatively great extent. In other places, such modifications may only have a relatively small effect on the magnetic flux. It is advantageous that the magnetic throttle point is realized or generated at a constriction for the magnetic flux to equalize the magnetic flux. As a result, the geometric extent of the modification can be kept small. For example, a recess on the ferromagnetic component, which forms the magnetic throttle point, can thereby be made comparatively small. As a result, other properties, in particular the strength of the component, not affected. This is advantageous, for example, in a modification which is made on a component formed as a housing part of a valve housing. If the magnetic throttle point is generated for example by a local microstructure transformation, then this can be a Reduced penetration into the component are possible. This facilitates the production, reduces the required for the structural change, introduced energy and thus avoids thermal damage and weakening of the material.

It is also advantageous that the modification of the ferromagnetic component, which is carried out to form the magnetic throttle point, is carried out on the end product or on a precursor in the form of an operable assembly. As a result, the magnetic flux can be adjusted for example by iterative energizing and force measurements as well as a machining of the component in order to set the desired value for the magnetic flux or for the magnetic tightening force.

The design of the magnetic throttle, which serves to balance the magnetic flux, specific properties can be influenced. This can be influenced by the orientation of the modified or removed material areas, the response of the magnetic circuit. For example, by a modification that runs transversely to the flow direction, an amount throttling of the magnetic flux can be achieved, which changes the maximum size of the closing force. By modifying along the flow direction of the magnetic flux can be influenced against the structure of eddy currents, whereby the temporal response of the magnetic circuit is affected. By the orientation of the modification and / or by the combination of suitable modifications, which can also be achieved by a plurality of magnetic throttle points, at least one property with regard to the response behavior can thus be influenced. Thus, within certain limits, in particular the increase and decrease of the magnetic attraction force and thus the closing force and, secondly, the maximum value of the closing force reached during a response or energization of the magnetic coil can be influenced in a targeted manner.

In the execution of the method, for example, it can first be determined how the magnetic actuator behaves. Due to the manufacturing tolerances in this case the response and the maximum amount of clamping force can differ from their target specifications. From this, in a possible embodiment of the method, modifications can be determined, which are subsequently realized on at least one component. In a further possible embodiment of the method, an iterative or continuous adjustment in the case of iterative or continuous measurement of the actual parameters is also possible.

Thus, a method is provided in which the magnetic flux and thus the closing force of the valve can be adjusted in the component and adjusted to a desired value without additional structural components are required. Depending on the embodiment, the method makes it possible to match essential functional variables of the magnetic actuator or of the valve. Such an essential function variable of the valve is, for example, a dynamic amount of liquid. Furthermore, a characteristic for the controlled valve operation can be stabilized. Thus, the tolerance-related dispersion around the desired properties can be reduced by individually adapting all products to the magnetic setpoint.

The operation of the adjustment of the magnetic actuators and / or the valves based on the change of the respective magnetic circuit in which the magnetic flux is passed through various components. This always includes a component which throttles the magnetic flux the strongest. The core of the adaptation is to create a magnetic throttle point artificially and to reinforce the relevant throttle effect until the desired state is reached. With the method, the scattering of the individual specimens can be limited in comparably precisely manufactured copies or allow the use of lower-cost components with coarser tolerances with constant dispersion of the magnetic force and similar properties.

The valve is preferably used for metering liquids. A preferred application is as a high-pressure injection valve or as a metering device for fluids for exhaust aftertreatment. In this case, a magnetic circuit is activated by applying a current to the magnetic coil, which leads to the activation of the valve and thus to the dosage. This magnetic circuit is determined by the components guiding the magnetic flux, in particular the air gap resulting from geometrical tolerances on the magnet armature and scattering in the magnetic properties of the components. Due to these manufacturing variations, the magnetic flux is always subject to fluctuations, resulting in functional variations, for example, in the dynamic dosing. In some valves, a control variable is generated as a functional relationship of applied current or voltage and closing time of the valve, which is used for the control of the products. In this case, a small dispersion of the magnetic circuit is also required, since otherwise the control mechanisms are adversely affected. Due to the magnetic throttle point, which serves to balance the magnetic flux, the scattering of the magnetic circuit can be limited to the required range for the control or regulation. As a result, the unfavorable influence of Control mechanisms prevented. The fluctuations in the magnetic flux generated by the manufacturing variations are at least partially compensated, thereby reducing the functional variations, in particular the dynamic metering.

Brief description of the drawings

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with identical reference numerals. Show it:

1 a magnetic actuator according to a first embodiment of the invention in a schematic sectional view;

2 a magnetic actuator according to a second embodiment of the invention in a schematic sectional view;

3 a magnetic actuator according to a third embodiment of the invention in a partial, schematic sectional view in a manufacturing step for explaining a method for producing the magnetic actuator;

4 a magnetic actuator according to a fourth embodiment of the invention in a partial, schematic sectional view in a manufacturing step for explaining a method for producing the magnetic actuator;

5 a valve, which is used for metering in an exhaust aftertreatment, with a magnetic actuator according to a possible embodiment of the invention in a partial, schematic sectional view and

6 a valve, which serves for the metering of fuel, with a magnetic actuator according to another possible embodiment of the invention in a partial, schematic sectional view.

Embodiments of the invention

1 shows a magnetic actuator 1 especially for facilities 2 of internal combustion engines is used. As valves 2 equipped facilities 2 are based on the 5 and 6 described. The magnetic actuator 1 has a magnetic coil 3 and ferromagnetic components 4 . 5 . 6 on. The ferromagnetic component 4 is in this embodiment as a pole pot 4 designed. The ferromagnetic component 5 is in this embodiment as anchor part 5 designed. The magnetic actuator 1 has an anchor 7 on, the anchor part 5 and a rod-shaped element 8th includes. Depending on the configuration of the magnetic actuator 1 This may be the rod-shaped element 8th also around a valve needle 8th or another actuator 8th act. By energizing the solenoid 3 is a magnetic flux (magnetic flux) 9 producible by magnetic field lines 10 . 11 is illustrated.

The magnetic actuator 1 is preferably at least approximately rotationally symmetrical with respect to an axis 15 designed. The anchor 7 is along the axis 15 adjustable within certain limits. About the energization of the magnetic coil 3 This is an actuation of the anchor part 5 and the rod-shaped element 8th along the axis 15 possible, what in one direction 16 he follows. In this embodiment, by energizing the magnetic coil 3 an actuation of the anchor part 5 and the rod-shaped element 8th in that direction 16 achieved. This is an air gap 17 between the anchor part 5 and the pole pot 4 closed. The provision is made via a suitable component, in particular a spring element 18 ( 5 ).

According to the magnetic field lines 10 . 11 This results in a magnetic circuit that passes over the ferromagnetic components 4 . 5 . 6 is closed. Here is the anchor part 5 with the rod-shaped element 8th connected. In the production of the magnetic actuator 1 arise due to manufacturing tolerances manufacturing scatters. Such manufacturing spreads may, if desired, within certain limits by adjusting the air gap 17 be compensated. However, this is usually only possible in batches, as an individual adaptation is very costly due to the required design effort.

For balancing the magnetic flux 9 with respect to a desired magnetic flux is at the ferromagnetic component 4 a magnetic throttle 19 realized. Here, in this embodiment, a structural transformation of a ferromagnetic material of the ferromagnetic component takes place 4 at the magnetic throttle point 19 , This structural transformation thus takes place locally to the magnetic throttle point 19 train. About the size of the magnetic throttle 19 or via the local extent of the local microstructure transformation takes place a more or less large influence of the magnetic flux 9 , This leads to a more or less pronounced attenuation of the magnetic flux 9 in relation to the initial state, in which the ferromagnetic material is still unaffected. The magnetic throttle 19 can be formed by local heating in this embodiment. In particular about the Amount of introduced energy for local heating may be the local extent of the magnetic throttle 19 to be influenced. In this case, the amount of heat introduced can be predetermined or determined by iterative or continuous measurement of an actual variable, in particular a magnetic tightening force.

The magnetic throttle 19 can, for example, by an austenitic microstructure 19 be formed of the ferromagnetic material.

2 shows a magnetic actuator 1 according to a second embodiment in a schematic sectional view. In this embodiment, the magnetic throttle is 19 through a recess 19 on the ferromagnetic component 4 educated. Here is the magnetic throttle 19 rotationally symmetric with respect to the axis 15 on the ferromagnetic component 4 educated. The recess 19 can be configured by laser processing. However, an embodiment of the magnetic throttle point is also 19 possible via a machining process.

3 shows a magnetic actuator 1 according to a third embodiment in a partial, schematic sectional view in a manufacturing step for explaining a method for producing the magnetic actuator 1 , To carry out the method is a generator 25 provided a laser beam 26 generated. The laser beam 26 is about a condenser lens 27 on a processing point 28 focused. Furthermore, an adjusting device 29 provided that ensures that the edit point 28 relative to the magnetic actuator 1 is changeable. In particular, the processing point 28 in this way around the axis 15 be rotated as indicated by the arrow 30 is illustrated.

In this embodiment, the processing point becomes 28 on that as anchor part 5 designed ferromagnetic component 5 directed. This will be the magnetic throttle 19 in this embodiment, on the anchor part 5 designed.

In addition, the magnetic throttle point 19 in this embodiment as a recess 19 in the ferromagnetic component 5 educated. By the rotation of the processing point 28 around the axis 15 also becomes the magnetic throttle 19 configured rotationally symmetrical.

Furthermore, via a force measuring device 30 , in particular as a force measuring device 30 can be configured, a magnetic tightening force during energization of the solenoid 3 measured. This can be iterative or continuous during machining of the ferromagnetic component 5 respectively. If the recess 19 is sufficiently large, so that the predetermined desired force for the magnetic attraction force is reached, then ends this production step. This is the magnetic flux 9 adjusted.

In this embodiment, the magnetic actuator 1 another ferromagnetic component 12 on, as a membrane 12 is trained. The magnetic field line 10 is here also on the ferromagnetic component 12 guided.

The generator 25 generates the laser beam 26 preferably as a pulsed laser beam 26 ,

4 shows a magnetic actuator 1 according to a fourth embodiment in an excerptive, schematic sectional view in a manufacturing step for explaining a method for producing the magnetic actuator 1 according to a further embodiment. In this embodiment of the method, the ferromagnetic component 6 processed. This is at a processing point 28 the ferromagnetic component 6 machined, creating a weld 19 is formed, which is the magnetic throttle 19 forms. The weld 19 in this case is preferably rotationally symmetrical with respect to the axis 15 on the ferromagnetic component 6 designed. About the blind weld 19 it comes to influencing the magnetic flux 9 , This can iteratively or continuously at a certain energization of the solenoid 3 generated anchor force on the force measuring device 30 be measured. This can cause the magnetic flux 9 be set to the desired magnetic flux. This is done indirectly via the setting of the anchor 7 acting magnetic force to a predetermined setpoint for this magnetic force. Thus, a balance of the magnetic flux 9 possible with respect to the desired magnetic flux with low production costs.

5 shows a valve 2 , which is used for metering in an exhaust aftertreatment, with a magnetic actuator 1 according to a possible embodiment of the invention in a partial, schematic sectional view. This is the magnetic actuator 1 within a multi-part valve housing 35 , the housing parts 36 . 37 includes. Here, one or more magnetic throttle points 19 . 19 ' on the magnetic actuator 1 be provided. About the valve 2 For example, a urea can be metered for exhaust aftertreatment.

6 shows a valve 2 , which serves for the metering of fuel, with a magnetic actuator 1 according to another possible embodiment of the invention in an excerpt, schematic sectional view. The rod-shaped element 8th is here as a valve needle 8th designed. The valve has housing parts 36 . 37 on. In this embodiment, the housing parts 36 . 37 of the valve housing 35 of the valve 2 Components of the magnetic actuator 1 , about which the magnetic flux 9 to be led. For tuning the magnetic flux can at the ferromagnetic component 4 a magnetic throttle 19 be formed. Additionally or alternatively, in this embodiment, also on the housing part 36 and / or on the housing part 37 restrictors 19 . 19 '' be formed to the magnetic flux 9 match.

The invention is not limited to the described embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006021741 A1 [0002, 0003]

Claims (12)

Magnetic actuator ( 1 ), in particular for institutions ( 2 ) of internal combustion engines, with a magnetic coil ( 3 ) and at least one ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ), one of the magnetic coil ( 3 ) caused magnetic flux ( 9 ) over the component ( 4 . 5 . 6 . 36 . 37 ) is feasible, characterized in that on the ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ) at least one magnetic throttle point ( 19 ), which is used to balance the magnetic flux ( 9 ) serves. Magnetic actuator according to claim 1, characterized in that at least one magnetic throttle point ( 19 ) by a local structural transformation ( 19 ) of a ferromagnetic material of the ferromagnetic component ( 4 ) is formed. Magnetic actuator according to claim 2, characterized in that the magnetic throttle point ( 19 ) is formed by an austenitic microstructure of the ferromagnetic material. Magnetic actuator according to one of claims 1 to 3, characterized in that at least one magnetic throttle point ( 19 ) through a recess ( 19 ) on the ferromagnetic component ( 4 . 5 ) is formed. Magnetic actuator according to one of claims 1 to 4, characterized in that at least one magnetic throttle point ( 19 ) by a blind weld ( 19 ) on the ferromagnetic component ( 4 ) is formed. Magnetic actuator according to one of claims 1 to 5, characterized in that the ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ) as at least substantially rotationally symmetrical component ( 4 . 5 . 6 . 36 . 37 ) is configured and that at least one magnetic throttle point ( 19 ) with a rotationally symmetrical configuration on the ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ) is formed and / or that the ferromagnetic component ( 4 . 5 ) as a polar body ( 4 ) or anchor part ( 5 ) is trained. Valve ( 2 ), which is used in particular for internal combustion engines, with a magnetic actuator ( 1 ) according to one of claims 1 to 6. Valve according to claim 7, characterized in that the ferromagnetic component ( 36 . 37 ) of the magnetic actuator ( 1 ) by a housing part ( 36 . 37 ) of a valve housing ( 35 ) is formed. Method for producing a magnetic actuator ( 1 ), which has a magnetic coil ( 3 ) and at least one ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ), via which one of the magnetic coil ( 3 ) caused magnetic flux ( 9 ) is feasible, characterized in that on the ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ) at least one magnetic throttle point ( 19 ) is formed so that one of the magnetic coil ( 3 ) caused magnetic flux ( 9 ), which is above the component ( 4 . 5 . 6 . 36 . 37 ), is balanced with respect to a desired magnetic flux. Method according to claim 9, characterized in that the adjustment of the magnetic flux ( 9 ) with respect to the desired magnetic flux so that one on an anchor ( 7 ) acting magnetic force is at least approximately equal to a predetermined target value for the magnetic force. Method according to claim 8 or 9, characterized in that the magnetic throttle point ( 19 ) by working the ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ) with at least one laser beam ( 26 ) is formed. Method according to claim 11, characterized in that the laser beam ( 26 ) as a pulsed laser beam ( 26 ) on the ferromagnetic component ( 4 . 5 . 6 . 36 . 37 ) acts.

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